This time he thought he heard a stealthy footstep.
"What is it?" called Tom from his chamber.
"Someone is in here!" exclaimed Ned. "Look out, Tom!"
CHAPTER XV
READY FOR THE TEST
Tom Swift acted promptly, for he realized the necessity. The events that had hedged him about since he had begun work on his giant cannon made him suspicious. He did not quite know whom to suspect, nor the reasons for their actions, but he had been on the alert for several days, and was now ready to act.
The instant Ned answered as he did, and warned Tom, the young inventor slid his hand under his pillow and pressed an auxiliary electric switch he had concealed there. In a moment the rooms were flooded with a bright light, and the two lads had a momentary glimpse of an intruder making a dive for the window.
"There he is, Tom!" cried Ned.
"What do you want?" demanded Tom, instinctively. But the intruder did not stay to answer.